1. Field of the Invention
The present invention relates to an electrolytic cell and to a process for the electrolytic reduction of a solution containing both titanium and iron values, and., more especially, to the electrolytic reduction of a solution emanating from the sulfuric acid decomposition of ilmenite.
2. Description of the Prior Art
It is known to this art that the production of titanium dioxide entails acidulating a titanium bearing mineral of ilmenite type, whether anatase or rutile, with a sulfuric acid solution. Following this acid attack, a solution containing titanyl sulfate and the sulfates of ferric and ferrous iron are obtained, in particular.
This solution must be reduced in order to convert the ferric ions into ferrous ions, as the presence of ferric ions must be avoided during the subsequent stage of hydrolysis of the titanyl sulfate.
Several techniques are also known to this art for such reduction of ferric iron. Industrially, it is carried out using "scrap iron".
This method has several disadvantages. In particular, it is discontinuous. On the other hand, it requires the subsequent separation of large amounts of iron which yield, notably, chips of ferrous sulfate.
Electrochemical reductions too have been proposed. One of these methods is specifically described in published French Application No. 2,363,642.
However, the different types of electrolyzers heretofore used do not enable the realization of good yields at high current densities, densities of at least 10 A/dm.sup.2.